Starting in the early twentieth century, the importance of air-transportation has drastically increased. Incentivized by the globalization of the markets in the last twenty years, the quantity of goods and people transported via aircraft has further increased worldwide. However, the pressure for cheap air transportation has also increased, resulting in downward pressure on prices and finally to the collapse of major airlines and aircraft operators at the beginning of the 21st century. Today, the price margins in air-transportation are extremely low, which forces the aircraft operators to a tight structure with only a small financial buffer in case of business interruption. In general, after 10 days without generating revenue in the sense of pooled returns due to performed operation, most of the major airlines would face the serious risk of being forced to stop operation or go out of business.